Safety device for elevators



N. o. LIND STROM SAFETY DEVICE FOR EIZEVATORS Jan, 29, 1929.

Filed May 10, 1926 2 Sheets-$heetllllillnll iilvll INVENTOR. W

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A TTORNEYJ Patented Jan. 29, 1929.

UNITED STATES PATENT orifice.

NILS O. LINDSTROM, OF NUTLEY, NEW JERSEY, ASSIGNOR TO A. 13. SEE ELEVATOR COMPANY, INC., A CORPORATION GIT DELAWARE.

SAFETY DEVICE FOR ELEVATORS.

Application filed May 10, 1926.

This invention relates to elevators, and more particularly to safety devices for preventing an elevator car from falling to the bottom of the shaft upon failure of its supporting means.

Devices of this character should be positive in action; and, at the same time, they should operate to stop the car gradually, rather than suddenly, in order to safe-guard the passengers and to avoid damage to -the car and its associated mechanism.

It has been customary to effect such stoppage by means of guide-rail gripping jaws, carried below the car and automatically rendered operative when the speed of the car exceeds a predetermined maximum. Such gripping aws have usually been actuated by wedge members controlled by various types of mechanical devices. For example, there have been employed means whereby undue speed of the car brings into action a tripping device to permit powerful springs to project the wedge members into engagement with the gripping jaws and to cause the latter to suddenly seize the guide rails with maximum gripping effect. Such devices are objectionable because of the abruptness of their action. It has also been proposed to actuate the wedge members by screw pressure, and various mechanisms have been used in attempts to apply such pressure with the nicety required to stop the car gradually, rather than suddenly.

lVhen elevators are initially installed, the guide-rails are properly aligned, so that the guide'shoes and the gripping jaws carried by the ear lit such rails with precision. However, as the building settles, the rails are thrown out of alignment and become uneven 1y worn by the action of the shoes. Unequal distribution of the load in the car tends to tilt the car with reference to the rails, and

this also causes uneven wear on the latte It is obviously highly desirable that the gripping effect shall be practically the same on both guide-rails, otherwise the car and its mechanism may be seriously strained and damaged; but it frequently occurs that one guide-rail wears more than the other, and uniformity of gripping action is thus rendered still more difiicult.

Serial No. 107,900.

It has been found that by reason of the foregoing conditions, devices which positively actuate the wedge members by screw pressure only, fail, aftercontimied use over considerable periods, to function with the degree of certainty which is requisite for bringmg the car to a gradual stop. Additionally, such devices have heretofore embodied many and quite complicated parts, which are expensive to manufacture and likely in time to get out of order, and, therefore, to fail to function properly when an emergency arises.

An object of my invention is to provide gripp ngaw actuating means of simple construction which can be economically manufactured, and which will continue, under actual operating conditions, to effect the desired nicely-graduated pressure between such aws and their coacting guide-rails. This object I obtain by the use of a system of floating wedges, and applying gear with cushioning means cooperating with the wedges. I

In the accompanying drawings Fig. 1 is a front elevation of a portion of an elevator shaft, including guide-rails, an elevator car, a governor cable and a safety cable.

Fig. 2 is an enlarged fragmentary detail in elevation of a governor cable socket, together with a mechanism normally associated with said socket to cause the car to drive the governmcable.

Fig. is a top plan view of the governor cable driving mechanism of Fig. 2, and a sectional detail of the cable socket on the line 3-3 of Fig. 2.

Fig. & is a view at the bottom of-tlie car. partly in elevation and partly in section, showing the guide-rails of the elevator shaft. a girder attached to the bottom of the car. and mechanism actuated by the safety cable for stopping the car.

Fig. 5 is a top plan view of the parts shown in Fig. 4. i

Fig. 6 is an enlarged fragmentary sectional detail on the line 66 of Fig. l, showing the safety device with its parts in position wherein the car is locked to the guide-rails.

Fig. 7 is an elevation of the left-hand side of Fig. l, with the guide-rail removed.

Fig. 8 is a sectional detail on the line 88 of Fig. 4, showing manually-operable means for re-setting the locking device after it has functioned.

Like reference characters indicate like parts throughout the drawings.

In the illustrated embodiment of the in vention, 1 represents an elevator shaft or hoist-way in which an elevatiirca'r is adapt ed to be raised and lowered as by cable 3. The shaft is provided with guide-rails 4 and 4% slidably engaging which rails are guit eshoes 5 and 53 mounted upon brackets 6 and 6, attached to girders 7 and 7, in turn mounted on the bottom of the car. Brackets (3 and 6 carry pivots 8 and 8*, Forming spectively, the tulcrums for guide-rail ping jaws '9 and 110 and 9 and 10. Jaws 9 and 10 are normally held out of engagement with guide rail 4 by one or more springs such as 11; and jaws 9 and 1O are similarly held out of engagement with guide-rail 4 by springs such as 11. The gripping jaws re-. spe'ctively are provided with rollers 12, 13, 12 and 13*. VVed e 14 is adapted to engage rollers 12 and 13, and wedge 14 to engage rollers 12 and 13 in order to cause the jaws to grip the guide-rails respectively. V] edge 14 is provided with supporting arms 15 and 16, having slotted ends engaging ways 17 and 18; and wedge 14 is similarly provided with supporting arms 15 and 16 engaging ways 17 and 18 Pivotally attached to wedge 14 is wedge-rod 19, and similarly attached to wedge 14* is wedge-rod 19. The opposite end of wedge-rod 19 is provided with a left-hand screw-thread, and the corresponding end of wedge-rod 19 is provided with a right-hand screw-thread. The thread ed portion of wedge-rod 19 engages an internal left-hand screw-thread formed in sleeve 20. and the corresponding portion of wedge- .rod 19 engages an internal right-hand screwthread Formed in sleeve 20. Sleeve 20 is splii'led by key 21 to the inner surface of safety cable drum 22, and sleeve 20 is similarly splined thereto by key 21. Sleeves 20 and 20 are thus adapted to be driven by the drum, and to move longitudinally in the hub portions 23 and 23 thereof. Hubs 23 and 23'" are rotatably mounted in, bearings '24 and 24 respectively, which bearings are supported on girders 7 and 7 Coiled spring 25 is positioned between sleeves 20 and 20and is'adapted to exert varying degrees of pressure upon said sleeves and their coacting wedge-rodsand wedgesdepending upon the degree of compression to which said spring is subjected.

Referring to 1 Mounted upon the top of the car is governor cable driving mechanism 26, normally engaging governor cable socket 27 todrive governor cable 28 over governor sheave 29 and over a coacting idler sheave (not shown) which is installed at the bottom of the elevator shaft. The purpose of the governor cable is to drive the governor, which is not shown in the drawings but the operation of which will be hereinafter described. Anchored to governor cable socket 527 is one end ot'saiety cable 30, which cable runs downward over sheave 31 (mounted on the bottom or the car) and around safety able drum '22, to which its opposite end is anchored. Referring to Figs. 2 and 8: Pin 32 of the governor cable driving mechanism 26 is mounted in governor cable socket 27. Arms 33 and 33 normally engage the ends of pin 32, being held in contact therewith by the action of spring 34. The tension of this spring is only such as is necessary, under normal conditions, to drive the governor cable 28 over its sheaves in order to actuate the governor, and to carry the safety cable along with the car. Referring to F 8: Worm wheel 35, attached to drum 22, is adapted to be engaged by worm 36 in order to re-set the safety device after it has functinned, and to re-wind safety cable 30 on drum 22. For this purpose, the worm is passed through an opening in the bottom of the car, inserted in its bearings, and manually rotated.

The mode of operation of the apparatus in the illustrated embodiment of the invention is as follows: hen the speed of governor cable 28 exceeds a predetermined maximum, the governor which is actuated thereby operates (in a manner well known to those skilled in this art) to firmly grip said cable and stop its travel over its sheaves. By reason of the downward movement of the car, governor cable driving mechanism 26 becomes disengaged trom socket 27 and the upper end of safety cable 30, which is attached to socket 27, being stationary, this downward movement of the car unwinos said cable fron drum 22, causing said drum to rotate in a clockwise direction. lVedg-es 14 and 14 being non-rotatable, the iirst etilect ot the rotation of the drum is as tollows: sleeves 20 and 20 being spliued to and rotated by the drum, they act as nuts to project wedge-rods 19 and 19, with their associated wedges 14 and 14, into contact with the rollers of the gripping jaws, whereby said jaws areeaus-ed to initially grip the guide-rails. When the resistance to the furt-her outward movement oi the wedges exceeds the force exerted by spring 25 upon sleeves 20 and 2O to maintain them in their outer positions (as shown in Fig. 4), said sleeves begin to travel together on their splines toward the center of the drum, in the progress of which travel spring 25 is progressively compressed. Simultaneously, wedges 14 and 14 are, by the continued rotation of sleeves 20 and 20 progressively projected further and further into; engagement with the gripping aws; but this positive projecting action is modified by the low cushioning effect of spring 25, which serves to equalize the pressure applied by the grip ping jaws to their respective guide-rails; and also to compensate for any irregularities in said pressure due to inequalities in the surfaces of the rails or jaws. My device is thus operative to effect a nicely-graduated and progressively-inereasing pressure between the grip-ping aws and the guic the widely-varying conditions which necessarily exist in elevator operation.

I claim 1. In an elevator safety device, the combination of guide-rail gripping means, positive actuating means for effecting initial contact between said gripping means and rails, and spring means for causing the yielding of said actuating means only after the resistance offered by the gripping means reaches a predetermined value.

2. In a safety elevator device, the combination of guide-rail gripping means, actuating means for said gripping means, a rotatable drum, means slidably mounted within said drum for operating said actuating means, and spring means for permitting said last named means to yield and cause the gripping means to be applied with spring pressure only after its resistance reaches a pre determined value.

3. In a safety device for elevators, the combination of guide-rail grip-ping means, wedge members for actuating said gripping means, a rotatable drum and means attached to and slidable in said drum for operating said wedge members.

4;. In an elevator safety device, the combination of guide-rail gripping means mounted upon the car and means for operating said gripping means splined to the inner surface of a rotatable drum controlled by the movement of the ear.

5. In an elevator safety device, a car frame, a plurality of guide members, a plurality of pairs of brake-jaw members having tail levers attached to said frame and cooperating with said guides, and means for the application thereof, comprising a safety cable drum, right and left hand nuts actuated thereby, right and left hand threaded push rods cooperating therewith, blunt ended wedges at tached thereto and cooperating with said brake members, guides therefor attached thereto and cooperating with said frame for positioning said wedge members with respect to said brake members, and anti-friction roller members attached to the ends of said friction jaw members and cooperating with said blunt ended wedge members, whereby said wedge members may be substantially withdrawn from between the tail ends of said brake member for the allowance of a maXimum clearance between said brake-jaws and said guides, whereby said wedges are adapted to enter between said friction jaw tail ie-rails, under members for the rapid movement thereof for the preliminary application of said brake members and whereby a further movement of said wedge members produces a slower-and more powerful final a plication.

6. An elevator safety device, comprising a car frame, elevator guides therefor, friction brake-jaw members attached to said frame and cooperating with said guides, wedge members cooperating therewith for the actuation thereof, right and left hand threaded push rods attached to said wedge members, a safety cable, a drum cooperating therewith, right and left hand nuts mounted within said drun'i, rotatable therewith, and cooperating wit id push rods, said nuts being movable endwise within said drmn, splines cooperating between said drum and said nuts for the rotation thereof, and a spiral spring within said drum cooperating with said nuts for the cushioning of forces produced by the rotation of said drum for the application of said brake members.

7'. An elevator safety device, comprising a car frame, elevator guides therefor, compri ing pivoted lever members having brake-j aws and tails, wedge members cooperating with said respective tails for the application of said brakes, and means whereby said wedge members are adapted to float between said tail members for the equalizing of application of said respective brake members.

8. An elevator safety device, comprising a car frame, elevator guides therefor, comprising pivoted lever members having brakejaws and tails, wedge members cooperating with said respective tails for the application of said brakes, and means whereby said wedge members are adapted to float between said tail members for the equalizing of application of said respective brake members, comprising a journaled safety cable drum, right and left hand nuts carried therein and spline-d thereto, whereby provision is made for axial movement thereof, and push rods having right and left hand threads cooperating between said nuts and said wedges.

9. An elevator safety device, comprising a car frame, guide members therefor, a pinrality of pairs of brake lever members having braking surfaces cooperating with said guides and tails adapted to the application thereof, means comprising wedges, rightand left threaded push rods, right and left threaded nuts, and a safety cable drum coopcrating therewith for the application thereof, and means comprising a protected cushioning spring cooperating with said nuts and enclosed within said safety cable drum.

10. In an elevator safety device, the combination of guide rail gripping means, 1ongitudinally movable threaded members for effecting initial contact between said gripping means and rails and means comprising spring pressed threaded members for actuat- Inn ing said longitudinally movable members, said spring pressed members being yiel'dable only after the resistance offered by the gripping means reaches a predetermined Value.

11. In an elevator safety device, the combination of guide rail gripping means, actuating means therefor comprising Wedges, 0ppositely threaded screws and nuts, and means for rotating said nuts, said nuts being slidablewith respect to said rotating means, and 10 spring means for holding said nuts against sliding until the :LGSlStfll'lCQ offered by the grnppmg means reaches a predeterm ned value.

In Witness whereof, I hereunto subscribe 15 my signature.

NILS O. LINDSTROM, 

